I’ve been organizing my Calibre library for years, and one thing I swear by is consistency in tagging. I start by using broad genre tags like 'fantasy', 'romance', or 'mystery' to keep things simple. Then, I add more specific tags like 'slow-burn' or 'enemies-to-lovers' for romance novels, or 'hard-magic' for fantasy. I avoid overly niche tags unless they’re truly useful—clutter makes searching harder. I also use series tags like 'Discworld_#1' to keep books in order. Calibre’s tag browser is a lifesaver, so I make sure my tags are clean and meaningful. Another tip: I batch edit tags using the metadata editor to save time. If a tag doesn’t help me find or remember the book later, I don’t use it.